[SPM Add Math Coordinate geometry] How to solve question (a) and (d)?


  1. Rajah 5 menunjukkan sebuah pentas segi empat sama A B C D yang dipasang pada tapak konkrit berbentuk bulatan berpusat K yang terletak di dalam tanah. P Q R S adalah paip saliran bawah tanah berbentuk segi empat tepat yang menyentuh tapak konkrit pada titik A dan C. Titik W dan V masing- masing ialah titik tengah paip QR dan PS. Diberi persamaan paip SCR ialah y-2 x=15.
    Diagram 5 shows a rectangular stage A B C D installed on a circular concrete with centre K which located in the ground. PQRS is a rectangular underground drainage pipe that touches the concrete site at points A and C. Points W and V are the midpoints of the Q R and PS pipes, respectively. Given the equation of SCR pipe is y-2 x=15.


Cari / Find,
a) Jarak CW,
CW distance

b) Persamaan garis AKC,
A K C line equation,

c) Koordinat K,
Coordinates of K,

d) Jika sebuah lagi pentas yang sama hendak dibuat dan berpusatkan di W, cari lokus bulatan pentas yang baru.
If another of the same stage is to be created and centered at W, find the locus of the new stage circle.


Hi Farhaini,
For part (a), I agree with your answer. Most likely there is an error in the mark scheme.

For part (d), we need to find the locus of the circle with centre W, and since the question mentions it is the same stage, the circle with centre W is identical to the circle with centre K: they have the same radius.


Since we have the coordinates of K and C,
we would just use the distance formula to find the radius of the circle.



so r=\sqrt{20}.

After we have r, we will just use the equation of a circle formula, where x_1 and y_1 are the x and y coordinates of W respectively.

I couldn’t get the answer given for (d) as well haha, not sure if I made any mistakes? If you agree with my answer then maybe there’s an error with the mark scheme :laughing:

Hope this helps! :slight_smile:

1 Like

Yeahhh your answer is definitely correct! Thank you very much! :relaxed::relaxed::grinning_face_with_smiling_eyes:

1 Like